Nest Substrate Research Articles

Importance of juniper to birds nesting in piñon–juniper woodlands in northwest New Mexico

AbstractPiñon–juniper (Pinus spp.–Juniperus spp.) woodlands are common throughout western North America, yet relatively little is known about the habitat use and requirements for many members of its avian community. During summer 2005–2007, we assessed avian nesting substrates within piñon (Pinus edulis)–juniper (Juniperus osteosperma) woodlands in northwestern New Mexico. Of all nests in live trees, 86% were in junipers. The selection of juniper as a nest tree was significantly higher than expected from the region's piñon–juniper ratio (1:1.06) for the community as a whole, for both open cup and cavity nesting species, and for 8 species (of which 6 are piñon–juniper obligate or semi‐obligate species). Nest survival, however, was not higher in juniper than in piñon for the nesting community as a whole or for chipping sparrows (Spizella passerina), the single species that was well represented nesting in piñon. The high use of juniper as a nesting substrate differs from previous studies, which have suggested that a presence of piñon is among the most important habitat features for many piñon–juniper species. Because of their importance to nesting birds, managers should avoid preferential thinning of junipers within piñon–juniper woodlands. © 2011 The Wildlife Society.

Role of topography, canopy structure, and floristics in nest-site selection and nesting success of canopy songbirds

Although oaks ( Quercus spp.) have historically dominated many forests in eastern North America, forest composition is changing due to anthropogenic impacts on disturbance regimes. Silvicultural practices, such as partial harvesting, are one component of management to promote oak regeneration. From 2007 to 2009 our research examined nest-site selection and nesting success for a guild of five canopy songbirds in upland mixed-oak forests in southeastern Ohio, USA. We monitored >700 nests across three state forests in both open canopy shelterwood stands harvested to approximately 50% stocking, and closed-canopy mature second-growth. Habitat attributes, including topography, canopy structure, and floristics, were measured at nest sites and random plots ⩽100 m from nests representing microhabitat available within the territory. Canopy songbirds selected specific topographic microclimates: Eastern Wood-pewees ( Contopus virens) nested on xeric ridgetops, Blue-gray Gnatcachers ( Polioptila caerulea) favored valleys, and Cerulean Warblers ( Dendroica cerulea) preferred productive northeast-facing slopes. Nest sites differed among species in terms of concealment, nest support, topographic position on the slope, and basal area of trees >38 cm dbh. Four of the five focal species selected Quercus alba as the nest substrate more than twice as much as available, and three species avoided Quercus rubra. Daily survival rates of nests were negatively associated with basal area of red oak species (both Quercus velutina and Q. rubra) for several species individually and across the canopy-nesting guild. Additional factors related to success included time of season for Eastern Wood-pewees, nest age for Cerulean Warblers, and concealment and size of the support branch for Scarlet Tanagers ( Piranga olivacea). In the long-term management for oak regeneration could benefit canopy songbirds, but our results indicate that white oaks, especially Q. alba, may be preferable to red oak species.

Effects of Fuel Reduction Treatments on Avian Nest Density in the Upper Piedmont of South Carolina

The Fire and Fire Surrogate Study is a national study installed at 13 sites across the United States. One goal of the southeastern Piedmont FFS installation was to assess the effects of fuel reduction treatments such as prescribed burning and thinning on avian nest density. Nest searching and monitoring took place within twelve 10-hectare study plots during the breeding seasons of 2003 and 2004. A total of 82 nests representing 23 species were discovered and monitored. Seventy-two percent of those nests were successful in fledging young and 28% failed. Higher quantities of herbaceous material, shrubs, and small diameter trees provided more nesting substrate in Thin/Burn and Burn plots. This study suggests that prescribed burning and a combination of prescribed burning and thinning may be beneficial for Southern Piedmont bird communities, but our conclusions must be considered in light of the small sample sizes of nests. Increasing the area of upland Piedmont forest receiving prescribed burning and thinning treatments could possibly benefit early successional species that are presently experiencing population declines across the United States.

Experimental Evidence that Sexual Displays are Costly for Nest Survival

AbstractNest predation is one of the most significant limitations for successful breeding of tropical passerines. Thus, parental strategies may include choosing appropriate nest sites and behaving in ways that minimize predation. Habitat characteristics that may influence nest success include degree of nest concealment, proximity to habitat edge, plant architecture as well as several others cited in the literature. However, few studies have examined display behavior as a factor that could also influence nest survival. We experimentally tested whether sexual motor displays served as a cue for visually oriented predators to locate artificial nests in a population of blue‐black grassquits Volatinia jacarina, a Neotropical passerine that exhibits a complex sexual display and is subjected to elevated rates of nest predation. We also evaluated the effect of nest substrate on survival. Predation rate was higher for nests within territories of displaying males relative to areas without displaying males and for nests placed in shrubs relative to grasses. Predation increased sharply in the third experimental replicate, at the end of the breeding season, which suggests that predators may develop a search image for nests or may become more abundant during specific periods of the season. Avian predators appear to be the most important nest predators. Results suggest that there may be a trade‐off between the increase in fitness derived from sexual displays of males to attract potential mates and the decrease owing to predation of active nests within their territories.

Facultative nest patch shifts in response to nest predation risk in the Brewer’s sparrow: a “win-stay, lose-switch” strategy?

Facultative shifts in nesting habitat selection in response to perceived predation risk may allow animals to increase the survival probability of sessile offspring. Previous studies on this behavioral strategy have primarily focused on single attributes, such as the distance moved or changes in nesting substrate. However, nest site choice often encompasses multiple habitat elements at both the nest site and nest patch scales. We studied the within-season re-nesting strategy of a multi-brooded songbird, the Brewer's sparrow (Spizella breweri), to determine whether pairs utilized a "win-stay, lose-switch" decision rule with respect to inter-nest distance, nest substrate and/or nest patch characteristics in response to previous nest fate. Pairs moved sequential nest sites slightly farther following nest predation versus success. When inter-nest distance was controlled, however, pairs changed nest patch attributes (shrub height, potential nest shrub density) associated with probability of nest predation to a greater extent following nest predation than success. The strategy appeared to be adaptive; daily nest survival probability for previously depredated pairs increased with greater Euclidian habitat distances between attempts, whereas previously successful pairs were more likely to fledge second attempts when nest sites were similar to those of previous attempts. Our results suggest that nesting birds can use prior information and within-season plasticity in response to nest predation to increase re-nesting success, which may be a critical behavioral strategy within complex nest predator environments. Re-nesting site selection strategies also appeared to integrate multiple habitat components and inter-nest distances. The consideration of such proximate, facultative responses to predation risk may clarify often unexplained variation in habitat preferences and requirements.

Effects of invasive woody plants on avian nest site selection and nesting success in shrublands

AbstractExotic, invasive plants are a growing conservation problem. Birds frequently use invasive plants as nest substrates, but effects of invasives on avian nesting success have been equivocal in past studies. In 2004 and 2005, we assessed effects of invasive woody plants on avian nest‐site selection and nesting success in western Massachusetts shrublands. At the nest scale, we tested the effects of invasive versus native substrates on nesting success as well as differences among individual invasive species. At the patch scale, we tested effects of invasive prevalence on nesting success in natives and invasives. We found that, as a whole, shrubland birds preferred invasive substrates. Of two species sufficiently abundant for individual analysis, gray catbirds Dumetella carolinensis preferred invasive substrates, but chestnut‐sided warblers Dendroica pensylvanica showed no preference for natives or invasives. At the nest scale, nests of gray catbirds placed in invasive substrates were more successful than those in natives. Chestnut‐sided warblers and all species combined, however, had equal nest success in invasives and natives. We found no differences in nest success for nests in different species of invasive substrates or in invasive substrates with and without thorns. At the scale of the patch, nest success in invasive substrates increased with the prevalence of invasives on a site. Nest success in native plants did not change with invasive prevalence. We attribute this finding to the tendency for thickets of invasive plants to be larger on sites with more invasive cover. These findings illustrate the complex interaction of different factors that can determine how invasive plants affect avian nesting success. We conclude that control of invasive woody plants should be neutral for most shrubland birds.

Effects of Rattus spp. Control Measures and Nesting Substrate on Nest Depredation, East Maui, Hawaii

We monitored natural and artificial nests during a two-part study on East Maui, Hawaii, designed to examine factors influencing nest depredation by black and Polynesian rats. The first half of the study examined the effects of rat control on nest depredation within portions of the Hanawi Natural Area Reserve. Rat density monitoring indicated control efforts had significantly reduced black rat captures in treatment areas, but no differences in survival of artificial or natural nests between treatment and control areas were observed. The second half of the study examined the effect of nesting substrate on nest depredation in the Makawao Forest Reserve during June 2003 and June 2004. We chose fruiting and non-fruiting nest substrates for artificial nests in two habitat types, native ohia/koa forest and an adjoining forest dominated by non-native tropical ash. Results from snap trapping showed that the relative density of black rats was significantly higher in the ohia/koa forest than the tropical ash forest, but plots with more rat captures did not always have higher rates of nest depredation as predicted. Our findings suggest that there is a large degree of variability in nest depredation by Rattus spp., but that rat density, forest type, and nest substrate influence nest depredation rates.

Genetic Assessment of the Mating System and Patterns of Egg Cannibalism in Atka Mackerel

AbstractThe mating system and patterns of gender‐specific egg cannibalism in Atka mackerel Pleurogrammus monopterygius were examined through genetic parentage analysis of embryos in egg clutches produced in captive and wild populations. Like other hexagrammid fishes, Atka mackerel exhibit polygynandry, which is characterized by serial matings by both genders within a breeding season. Most matings in captivity were pairings of females with nest‐attendant males, although parentage analysis of clutches produced in a small tank with limited nesting substrate revealed that 31% contained contributions by non—nest‐guarding males. In contrast, all egg clutches produced in a large exhibit tank were sired by guardian males. Multiple parentage, sometimes involving both genders, was detected in 35% of egg clutches collected in the field or retrieved from the guts of adult male and female cannibals. Half‐sib and unrelated full‐sib embryos were found in several putative clutches, indicating that the reproductive output from multiple males and females may be combined sequentially and fused into a single clutch. These results suggested that nest takeovers, combined with alloparental care of existing broods, represent common reproductive tactics in males. Egg cannibalism is a significant seasonal factor in the diets of male and female Atka mackerel. Analysis of loose eggs and partial egg clutches ingested by 4 female and 15 male cannibals showed that nearly all conspecific predation represented heterocannibalism. One instance of partial filial cannibalism was documented in a male that was one of multiple sires for the clutch.

Black-Chinned Hummingbird Nest-Site Selection and Nest Survival in Response to Fuel Reduction in a Southwestern Riparian Forest

Despite widespread efforts to avert wildfire by reducing the density of flammable vegetation, little is known about the effects of this practice on the reproductive biology of forest birds. We examined nest-site selection and nest survival of the Black-chinned Hummingbird (Archilochus alexandri) in New Mexico riparian forests treated or not for fuel reduction. In untreated plots the hummingbirds frequently nested in exotic trees such as saltcedar (Tamarix spp.) and Russian olive (Eleagnus angustifolia). Following fuel reduction, they increased use of cottonwood (Populus deltoides ssp. wislizenii) as a nest substrate and nested at greater heights. Though fuel reduction influenced habitat and nest-site selection, it did not immediately affect nest survival. A logistic exposure model containing effects of year and interaction of nest height and substrate explained nest survival better than did other models. Estimates of daily nest-survival rates from this model varied by year from 0.970 (95% CI: 0.949– 0.982) to 0.992 (95% CI: 0.983–0.996), corresponding with period survival rates of 31% (95% CI: 13.7%–50.1%) to 73% (95% CI: 52.1%–85.9%). In addition, in all substrates except saltcedar, nest survival decreased with nest height. Our relatively high nest-survival estimates suggest that the riparian forest along the Middle Rio Grande provides high-quality nesting habitat for this species. Fuel reduction, however, reduces nest-site availability and can lower nest survival by removing potential nest sites in the forest understory, forcing hummingbirds to nest at greater heights where predation risk is higher.

Dermestid Beetles Inhabiting Wading-Bird Nests in Northeastern US Estuaries

Abstract Ectoparasitism of nesting birds is known to impact reproduction for many species including cavity-nesting swallows and ground-nesting colonial seabirds. Little information is available from wading birds (e.g., herons, egrets, ibises). We documented skin-eating dermestid beetle abundance in 261 wading-bird nests in seven heronries located in northeastern US estuaries during 1991–2000. Beetles were collected after fledglings were no longer using the nest. We examined all twigs and debris for larval and adult beetles, and excavated holes in twigs to count pupating insects. In addition, nest size was evaluated. Dermestes nidum (dermestid beetle) larvae were prominent members of nest faunal communities in all estuaries. We detected no evidence that beetle abundance correlated with wading-bird species, nest reuse, nest substrate species, or nest-collection date. Regression analysis and partial correlation analysis identified nest size, colony, and year as factors showing a significant relationship with...

Substrate choice of territorial male Topeka shiners (Notropis topeka) in the absence of sunfish (Lepomissp.)

Abstract – Topeka shiners (Notropis topeka), an endangered minnow species, typically spawn on or around breedingLepomissunfish (Centrarchidae) nests. Why spawning Topeka shiners are attracted to these nests is unclear, but having the nesting sunfish provide shiner eggs with improved aeration, a lessening of siltation, and protection from egg predators are possibilities. We tested the substrate utilisation of Topeka shiners in outdoor tanks in the absence of sunfish to determine the shiner’s fundamental choice. Shiners were provided with substrate patches of cleaned sand, small gravel, large gravel, and small cobble, and the bare floor of the tank. The substrate above which a male shiner established his territory was used as evidence of choice. A statistically significant choice for sand substrates was demonstrated. This fundamental choice might influence which sunfish nests Topeka shiners use, given that nest substrate characteristics differ both between sunfish species and within species by spawning site location.

Lack of biological effects of water accommodated fractions of chemically- and physically-dispersed oil on molecular, physiological, and behavioral traits of juvenile snapping turtles following embryonic exposure

Snapping turtle ( Chelydra serpentina) eggs were exposed to two concentrations of chemically- or physically-dispersed water accommodated fractions of weathered Arabian light crude oil (Low = 0.5 and High = 10 g oil/L water). Solutions were passed through nest substrate to simulate alterations in composition during percolation to egg depth. Hatchlings were raised for 13 months during which numerous endpoints were measured. Prior to percolation, total PAH (“tPAH”; the sum of 52 PAHs measured) in physically-dispersed oil fractions were similar (High, 43; Low 67 mg/L). Following percolation, tPAH was also similar in physically-dispersed fractions (High, 14; Low 24 mg/L). Addition of dispersant increased tPAH prior to percolation in the High treatment (302 mg/L) relative to Low (13 mg/L), but percolation resulted in nearly equal concentrations in both treatments (High, 30; Low, 22 mg/L) due to physical trapping of dispersed oil by the nest substrate. In both chemically- and physically-dispersed fractions, percolation reduced low molecular weight (MW) compounds such that embryos were exposed to primarily mid- to high MW compounds. Total PAH in eggs differed 15-fold between the chemically-dispersed High and physically-dispersed High treatments (560 and 36 µg/kg respectively), the former characterized by higher MW compounds than the latter. While eggs accumulated up to 560 µg/kg tPAH, we observed no effects on hatching success or hatchling/juvenile traits (DNA integrity, survival, growth, metabolism, energy storage, or behavior), our results demonstrate that PAH profiles are altered during percolation, suggesting that experiments with subsurface organisms should be designed to account for compositional changes that occur as the solutions percolate through the substrate.

Genetic Structuring at a Fine Scale in the Russet-Crowned Motmot (Momotus mexicanus) in a Tropical Dry Forest in Central Mexico

Because of their high dispersal abilities, birds are expected to manifest marked genetic structuring only at relatively large geographic scales. However, it is not well known how factors like nest site fidelity in a largely resident species could limit gene flow and increase genetic structuring in birds. In this study we use RAPD markers to estimate genetic structuring in a strongly sedentary species of the American tropics, the Russet crowned Motmot (Momotus mexicanus), within a tropical dry forest in central Mexico. Genetic structuring was assessed among 3 populations separated by a mean distance of only 25 km. We report that 12.9% of the total genetic variation is explained by differences among sites, which is quite high for a bird at this geographic scale. We propose that high nest site fidelity, brought on by a scarcity of suitable nest substrates, may be responsible for high genetic structuring in this species.

Effects of nest substrate on egg deposition and incubation conditions in a natural population of fathead minnows (Pimephales promelas)

Fathead minnows ( Pimephales promelas Rafinesque, 1820) occur commonly in small lakes across the prairie region of North America. Males establish nests, court females, and tend the eggs. In our study population in Minnesota, males choose between two distinct nest substrates that differ in exposure to abiotic conditions affecting egg development: the underside of pond-lily (genus Nuphar Sm.) pads or the underside of submerged sticks. We found that lily pad nests contained more eggs, more clutches of different ages, and eggs distributed over a larger area than nests under submerged sticks. The difference in egg incubation temperatures between lily pad nests and stick nests varied diurnally with air–water temperature gradients. Proximity to the surface allowed lily pad nests to be significantly warmer during the day but only slightly cooler at night than nests under submerged sticks, resulting in about 10 h shorter time to hatch. The availability of lily pads for nests may greatly alter selection on sexual behaviour by males in competing for limiting nest sites of high quality, and female opportunity to exercise choice of mate. Moreover, availability of lily pads changes the role of abiotic conditions. In warm weather, males that nest under lily pads may achieve greater reproductive success than males that nest under sticks.

Nest site restoration increases the breeding density of blue-tailed bee-eaters

For birds that excavate their own nest burrows, the availability of suitable nest sites and substrates may influence the number and density of breeding birds. However, few studies of burrow-nesting birds have experimentally manipulated nest site or substrate availability. The blue-tailed bee-eater ( Merops philippinus) is a colony breeding, summer migrant that excavates nest burrows in sandy banks on Kinmen Island, 5 km east of mainland China. To test whether substrate availability influenced the density or reproductive success of breeding pairs of bee-eaters, we removed all vegetation and old nest holes on treated slopes and left control slopes unmanipulated in 2003 and 2004. Plant cover on control slopes was 37.7% (11.9–67.7%). Slope gradient, soil penetration resistance and vegetation height in front of slopes did not differ between treated and control slopes in either year. Combining data from both years, the density of active nests was significantly higher (3.1-fold) on treated slopes than on control slopes. However, the reproductive performance of bee-eaters nesting on treated and control slopes did not differ in either year. Thus, removing vegetation and old nest holes from slopes with sandy loam soil improved the breeding habitat and increased the number of breeding blue-tailed bee-eaters. This technique could be used to support and manage populations of this species and other burrow-nestling species with similar habitat requirements.

Evaluation of Factors Restricting Distribution of the Endangered Key Largo Woodrat

ABSTRACT We examined a suite of models in an information theoretic framework to identify factors restricting presence of the endangered Key Largo woodrat (Neotoma floridana smalli) throughout its remaining habitat. Models containing variables related to availability of nest sites and mammalian predator abundances were supported by our data. Abundance of natural (large overstory trees) and artificial (rock and debris piles) nest substrate were the most important predictor variables, followed by indices of feral cat and raccoon (Procyon lotor) abundance. We recommend increasing abundance of nest substrate in the short term through addition of artificial nest substrate and in the long term through continued protection of remaining forest habitat.

PO2in Loggerhead Sea Turtle (Caretta caretta) Nests Measured Using Fiber-Optic Oxygen Sensors

Abstract The environment sea turtle embryos experience in the nest is determined by the needs of the growing embryos and the ability of the nest substrate to transport heat, water, and respiratory gases to meet those needs. Relatively little is known of the PO2s in natural sea turtle nests, and what is known has been obtained through methods which may alter the nest PO2 during measurement. I describe a noninvasive means of measuring sea turtle nest PO2 using fiber-optic O2 sensors. I found that both the rate of nest PO2 decline and the minimum nest PO2 varied considerably among Loggerhead Turtle (Caretta caretta) nests. Nests exhibited rates of decline and minimum PO2s that ranged from 0.07 to 0.19 kPa/day and 11.4 to 16.4 kPa, respectively. No difference in minimum nest PO2 was observed between nests that were relocated and those left in situ. The mean minimum nest PO2 in this study (13.8 ± 0.21 kPa) is in agreement with other measurements of nest PO2, but the rate of PO2 decline measured in this study s...

Nest distribution and nesting habits of Xylocopa ordinaria Smith (Hymenoptera, Apidae) in a restinga area in the northern Rio de Janeiro State, Brazil

This paper aims to study the distribution of natural nests of Xylocopa ordinaria and characterize its nesting habits in the restinga of Grussai/Iquipari (RJ), supporting future studies on the pollinators management in the northern Rio de Janeiro state. The data obtained from Aug/2003 to Dec/2004, in an area of 11.6ha, were related to the nest distribution, substrate identification and dimensions, emergence, sex ratio, nest structure (n= 23 nests) and pollen content analysis of provisioning masses and feces. X. ordinaria nests were abundant and presented a clustered distribution. These bees do not present taxonomical affinity for nesting substrates, but preferences for wood availability and characteristics, being Pera glabrata the main substrate. X. ordinaria is a multivoltine species that tolerates co-specifics in their nests. These bees were generalist on their nectar and pollen consumption, but presented floral constancy while provisioning brood cells. These behaviors, activity along the year, flights throughout the day, and legitimate visits to flowers indicate the importance of X. ordinaria on the pollination of plants in the restinga.

NEST-SITE CHARACTERISTICS AFFECT DAILY NEST-SURVIVAL RATES OF NORTHERN APLOMADO FALCONS (FALCO FEMORALIS SEPTENTRIONALIS)

Abstract We modeled daily nest-survival rates (DSR) of a reintroduced population of Northern Aplomado Falcons (Falco femoralis septentrionalis; hereafter “falcons”) in southern Texas. Although falcons have nested in the region since 1995, the factors influencing reproductive success are not understood. Nest sites were classified into nest-type groups using a cluster analysis based on nest substrate and nest builder. Using an information-theoretic approach, we compared relative effects of nest age, study area, nest-type group, and physical nest-site characteristics. Our results were similar to previous studies of passerine nesting ecology, in that DSR varied throughout the nesting cycle: it was constant during incubation, declined at hatching and the early nestling phase, and increased through the remainder of the nestling phase. Nest type and nest height were important physical nest-site covariates, overhead cover was less important, and study area and nest initiation date were not influential. We note th...

An experimental approach to understanding the use of mistletoe as a nest substrate for birds: nest predation

Recent research has documented an unprecedented diversity of birds using mistletoes as nest-sites, and a strong preference for nesting in mistletoes has recently been demonstrated for some species. The consequences and underlying reasons for this behaviour have not been evaluated, and it is unclear whether nests in mistletoes confer advantages compared with other available substrates. Nest predation is often cited as the most important factor regulating many bird populations and is thought to influence all aspects of nest-site selection. To evaluate whether nest predation may play a role in the widespread use of mistletoe as a nest-site, we conducted an artificial nest predation experiment in a eucalypt woodland in southern New South Wales, Australia. Artificial nests were modelled on noisy friarbird (Philemon corniculatus: Meliphagidae) nests, baited with a single quail egg and checked after four days. We used logistic regression to model the rate of depredation between plant substrates, and demonstrate that, in this experiment, mistletoe nests experienced a lower proportion of predation than eucalypt nests (51.5% versus 63.8% respectively). This finding suggests that predation may influence the widespread use of mistletoe as a nest-site in a range of habitats and regions. In addition to clarifying priorities for further work on mistletoe nesting, this finding has implications for studies of nest-site selection generally, with researchers encouraged to supplement between-substrate comparisons with direct measurements of within-substrate variation.